1. Field
Subject matter disclosed herein relates to measuring waveguides, such as, for optical fibers or planar waveguides, for example.
2. Information
Waveguides, such as optical waveguides, including, for example, planar waveguides and/or optical fibers, may guide electromagnetic radiation, commonly referred to as “light,” in one or more transverse modes. Likewise, the terms electromagnetic radiation and optical signals or similar terms are used interchangeably. A transverse mode with respect to a beam of electromagnetic radiation refers to an electromagnetic field pattern of radiation that may be measured in a plane substantially perpendicular or transverse to beam propagation direction. Waveguides that support multiple propagation paths, e.g., more than one transverse mode, for example, are called multi-mode waveguides. Likewise, optical fibers that support multiple propagation paths, such as more than one transverse mode, for example, are called multi-mode fibers (MMF), while those that support a single transverse mode are called single-mode fibers (SMF).
Optical waveguides (e.g., optical fibers) may be incorporated into any of a variety of devices. An example of a device comprises a beam combiner that is able to multiplex optical signals from multiple optical fibers into a single optical fiber. Another example of a device incorporating optical waveguides comprises a mode field diameter adaptor in which a mode field of a fiber may be converted to a differently-sized and/or differently-shaped mode field. Yet another example of a device comprises an optical fiber amplifier in which optical signals, which may travel along or through an optical fiber, such as via a core-guided mode, may be amplified by providing additional optical energy, such as via an optical pump, for example.
In many types of optical fibers, optical fiber devices, or more generally waveguides, a useful parameter may involve distribution of optical energy among various guided modes, which may, for example, include one or more modes guided by a fiber core and also may include one or more modes guided by cladding material. Mode or modes, of course, are understood to refer to a guided mode or to guided modes. Understanding energy distribution across various modes and/or energy exchange between various modes for a waveguide (e.g., an optical fiber or an optical fiber device) may be desirable for a variety of reasons, including, for example, evaluating performance of potential devices that may employ waveguides, such as fibers.